Plastering of aerated concrete walls: technology, necessary equipment. How to plaster walls from gas silicate blocks? How to plaster gas silicate blocks indoors

Plastering of aerated concrete surfaces is a necessary measure due to the fact that the porous structure of the material allows moisture to pass through well, and this is unacceptable for the durability of any residential building. Aerated concrete bricks are highly hygroscopic. Therefore, facade plaster for aerated concrete is applied without fail, preferably in two layers, and with preliminary protection of the walls with a primer and antiseptics.

Any atmospheric precipitation is the risk of wetting the walls of gas blocks, which, after drying, can begin to collapse, becoming covered with microcracks inside and outside the house. And this risk increases markedly in winter, because the water in aerated concrete, when frozen, will expand and burst the building material, violating its monolithic structure.

Before plastering the facade and side walls of the house, especially in winter, the outer surface must be protected from moisture with a polyethylene film. After obligatory plastering, any decorative material for the exterior cladding of the facade can be attached to the surface finished with mortar.

Purpose of finishing outside:

Increasing the heat and noise insulation of the building and premises;
Minimization of the probability of wetting the walls with precipitation;
Protection of external surfaces from contrasting outdoor temperatures;
decorative feature.

The application of plaster is the most common method of finishing facades and walls made of aerated concrete due to its relative cheapness and ease of execution. But even such a simple process requires study, so a small overview of the characteristics of the plaster compositions used in construction for outdoor work and the methods of plastering aerated concrete surfaces will be useful.

Three types of practical and cheap building materials for wall decoration are common, therefore, how to plaster aerated concrete should be decided after studying all the options:

Cement-sand mortar

This is the most common internal plaster mixture for builders, but it is not recommended to use it for plastering gas blocks from the outside, since the gas brick does not hold cement well. And, if a primer or fiberglass mesh can be used on the walls inside the house to hold the plaster cement-sand mortar, then these methods are not suitable for working outside due to the constant exposure to temperatures and precipitation. It is undesirable to protect gas blocks with a cement-sand mortar, since gas blocks immediately absorb moisture from the mixture. The reasons for the ban are as follows:
1. The cement-sand mixture has a lower vapor permeability coefficient than aerated concrete. And the most important rule of the plasterer is to use a material whose vapor permeability coefficient is the same as this indicator or greater than that of aerated concrete;
2. Expanded polystyrene or polystyrene is not recommended to insulate the house for the same reason.
The plaster applied on aerated concrete on cement contains a lot of water, since it is kneaded on it. Aerated concrete is initially produced with a high moisture absorption coefficient, so moisture from the solution will quickly get inside the wall, leveling the adhesion, layer quality and strength of aerated concrete blocks, because the main condition for the strength of concrete is slow setting and hardening;
Cement-sand mortar has low adhesion, that is, adhesion. Therefore, for plastering internal walls, lime can be added to the solution in proportions of 1:10 (lime - cement);
The cement mortar must be covered with a finishing layer of plaster, as the starting layer will be rough.

Construction adhesive mixture

Construction adhesive is a very expensive solution, and it is impractical and uneconomical to apply it in a large layer instead of plaster;
When plastering aerated concrete blocks with a building adhesive mortar, the vapor permeability of aerated concrete will decrease, since the glue does not pass air well. As a result of clogging of the pores in the blocks, the material may begin to crack, mold may appear in poorly dried places, local peeling of the adhesive plaster is possible.

Gypsum for aerated concrete

The positive aspects of plastering with gypsum mortar:

Gypsum plaster mixture quickly sets and dries;
Gypsum mortar does not shrink;
Even a thin plaster surface will be smooth;
For such plaster, a finishing decorative layer is not needed.

Flaws:

The vapor permeability coefficient leaves much to be desired;
Large water consumption;
Any atmospheric precipitation moistens the gypsum plaster to the entire depth of the layer;
Due to too good adhesion, colored spots may appear on the surface due to the penetration of mineral dyes in the composition of aerated concrete into the gypsum layer.

Gypsum or alabaster is considered the most effective composition for plastering aerated concrete surfaces outside and inside the house. This mixture for facade finishing works has a vapor permeability coefficient equal to that of aerated concrete, excellent adhesion, and an attractive appearance.

What kind of plaster is better to plaster aerated concrete walls?

There are special mixtures for working on aerated concrete. It is preferable to use mixtures with the following properties:

High or medium vapor permeability;
Not more than 200 ml of water per 1 kg of the mixture for its mixing;
The minimum and maximum thickness of the plaster layer (the greater the difference, the better);
Index of adhesion with the main surface - ≥ 0.5 MPa;
Resistance to low temperatures;
Crack resistance;
Long working solution life.

Conditions for plastering aerated concrete surfaces

Carrying out plaster work in the warm season involves the rainy season, but getting wet aerated concrete blocks is not as critical as freezing the moisture inside them. Therefore, it is better to protect the aerated concrete dwelling with moisture-proof films at any time of the year, since the walls may simply not have time to dry in the fall before frost.

The newly erected walls of the house must dry out before they are plastered, therefore both construction and plastering on aerated concrete should be carried out in the summer. Due to the fact that the first row of gas bricks is usually laid on a cement-sand mortar, the drying time of the walls increases, and this circumstance must be taken into account when calculating technological processes.

Applying two or three layers of primer to aerated concrete will significantly reduce its water absorption. The practice of building private housing has shown that the best time to build aerated concrete walls of a building is the season when the temperature at night does not drop below 0 ° C.

There are three options for finishing aerated concrete surfaces, taking into account the order of finishing work:

The first is the exterior finish. Private developers mistakenly think that first of all it is necessary to protect the house from the outside so that the walls do not get wet from rain and snow. But even wet in the fall, but primed aerated concrete in the spring will quickly dry at positive temperatures. With walls covered with plaster, moisture in winter will only evaporate inside the housing, which will not only extend the drying time of the walls, but also affect the occurrence of cracks on the internal walls of the house;
The first is interior decoration. With such an organization of the process, the moisture accumulated in aerated concrete has only an outlet to the outside, and the possibility of cracks will be minimal. Therefore, this finish option is considered the most correct;
Exterior and interior decoration is carried out simultaneously. This option is the worst of all three. Moisture in gas blocks is clogged, and its slow evaporation will lead to cracks, mold, and peeling of the plaster layer.

Internal plastering technology

Before plastering the walls, they must be leveled with a special planer, grinder or grater on aerated concrete. Leveling will help save on the thickness of the plaster layer - if you apply too thick a layer, the plaster may begin to crack or even peel off.

Sanded walls should be primed, but it is not recommended to dilute the primer with water. Then metal beacons are attached to the walls - 2-3-meter perforated ribbed corners that determine the thickness of the plaster layer. The corners are attached to plaster or alabaster, the distance between them is determined by the width of the rule or the widest spatula. The verticality of the fastening is checked by level.

On the walls for aerated concrete, the plaster is applied from the bottom up, and leveled with the rule. Voids and irregularities are filled with mortar using a smaller spatula. After an hour and a half, when the first layer of the solution has set a little, it is moistened with a spray bottle, and leveled with a wide spatula (rubbed). It is desirable to remove lighthouses before this operation, as they can serve as the point of occurrence of "cold bridges". The inner corners are aligned and reinforced with the same beacons, the outer corners are reinforced with a metal perforated corner without ribs, and a fiberglass mesh. After the last layer has completely dried, the wall must be rubbed.

If the interior walls are to be painted, it is recommended to use a paint with good vapor permeability, for example, acrylic, water-based or PVA-based paints, as well as those based on organic solvents.

How to plaster aerated concrete inside the house updated: January 23, 2017 by: Artyom

Recently, aerated concrete has been used in the construction of private houses. The material has earned wide recognition due to its positive qualities. Such material is produced in rather voluminous blocks of light weight, so construction is carried out at a fast pace.

Peculiarities

The foam material perfectly retains heat, therefore, you can significantly save on insulation.

The abundance of pores allows the blocks to "breathe". The bad thing is that they absorb moisture. If in the warm season the water dries up without consequences, then in frost the moisture absorbed into the building material will inevitably lead to the formation of cracks.

Plastering aerated concrete will prevent the penetration of water into the block, maintain its integrity.

For high-quality performance of work, it is necessary to take into account the features inherent in the material being processed. Not all aerated concrete blocks are the same - their structure may differ. For example, the outer surface is different.

Sawn aerated concrete can be plastered without pre-treatment. The molded block has a smooth hydrophobic layer on the outside. It is problematic to apply plaster on such a surface - to increase adhesion, it is necessary to grind the treated side with a metal brush.

We must not forget that the degree of vapor permeability increases in the direction from the inner surface to the outer, so the facade decoration should be done twice as thin as the inner coating.

Before plastering aerated concrete walls after construction, at least six months must pass. During this time, the walls will dry completely, excess moisture that gets into the blocks during the construction of the building will disappear from them.

The outer surfaces of the walls can be plastered with decorative materials, compositions for subsequent painting can also be used. External decoration sometimes serves as additional insulation. In regions with a cold climate, plastering plays a significant role in keeping the heat inside the premises.

For aerated concrete, plaster with optimal parameters should be chosen. Finishing material must protect the walls from destruction on both sides.

Due to the porosity, aerated concrete has received such characteristics as thermal insulation and vapor permeability.

Proper Finishing:

helps to preserve the useful qualities of the blocks;
does not allow condensate to accumulate inside the pores;
prevents mold and unwanted damage.

Types and compositions

It is impossible to finish aerated concrete walls with ordinary cement mortar. Standard solutions have too much density, so they do not set well with blocks. Due to poor adhesion, after a short time, cracks appear on the walls, which leads to peeling of the plaster layer and exposing the walls.

Special "breathable" mixtures with a so-called vapor-permeable base:

steam passes freely;
create a positive indoor climate;
protect the walls from the accumulation of moisture inside them.

The following requirements are imposed on plasters for finishing aerated concrete:

resistance to precipitation and ultraviolet, to rapid and frequent changes in outdoor temperature;
sufficient density;
high adhesion;
the presence of vapor permeability;
compressive strength;
good thermal insulation;
decorative appearance.

Good plaster meets all of these requirements. It is easy to apply, looks great and stays on the walls for a long time.

If the facade is not processed, then the aerated concrete will first darken, then it will begin to deform, and its outer part will peel off.

Exterior plasters are different from those used for interior finishing of aerated concrete blocks. The former are more expensive, the latter are cheaper. The main difference lies in the ability of the hardened mixture to resist moisture. If for external walls this indicator is essential, then for interior decoration you can do without it. The exception is plaster for rooms with high humidity. such as bathrooms.

By composition, facade plasters are divided into the following types:

acrylic;
silicone;
silicate;
lime-cement.

None of the species can be considered ideal - each variety has its own strengths and weaknesses. For example, the vapor permeability of acrylic-based plaster is low, but it has excellent decorative properties. The finish is thin, but very durable. The layer retains an impeccable structure for a long time.

It is advisable to use acrylic plaster when applying good insulation to interior walls.

The basis of silicate plaster intended for aerated concrete is liquid potash glass. The vapor-permeable covering is resistant to moisture, perfectly resists attrition and pollution. Durability is a quarter of a century. The disadvantages include a limited range of colors.

The composition of silicone mixtures includes organosilicon polymers and resins. The cover is very durable. Unlike other types of silicone plaster, it remains elastic after curing. Cracks do not appear on the finishing layer even after shrinkage of the blocks. Due to the fillers, the plaster is given various colors and shades.

The advantages have a significant impact on the cost - silicone mixtures are the most expensive.

Lime-cement mortars are characterized by vapor permeability and strength. They lack elasticity and water resistance. The problem is solved by introducing special additives into the mixture, and experimenting with fillers, you can get different colors.

Ready mixtures are equipped with everything you need - they can be used without prior preparation and the introduction of improving components.

For internal work, completely different compositions are used. Gypsum is present in the basis of plaster for processing aerated concrete indoors.

Before starting work, the blocks should be primed.

The plaster is applied to a leveled surface, free from build-up, dirt and dust.

The work is carried out in several stages:

padding;
applying the first layer of plaster;
installation of reinforcing mesh;
applying a second layer of plaster.

Wallpaper can be glued onto the treated wall after the material has completely dried.. Optionally, you can perform a decorative finish. The decor appears when fillers in the form of marble chips or perlite are introduced into the gypsum mixture. A wall covered with gypsum mortar can be painted.

Training

It is very important that the aerated concrete walls are prepared for the application of the finishing layer.

Despite the fact that the outer and inner parts of the wall are operated under different conditions, there are general requirements for their pre-treatment:

both inside and outside the walls must be even;
for both sides, the plaster should be chosen with maximum adhesion ability;
applying the solution to the mesh is desirable on both sides;
the master will need a container for mortar, a trowel, a plaster ladle, a grater.

In order for the plaster to fit well on the gas blocks, the latter should be evenly moistened. For this, ordinary tap water and a simple sprayer are suitable.

If there are chips or cracks, then you will have to pick up a trowel and use the solution to eliminate the flaws. Cement mortar will be an excellent restoration material if the recesses are first treated with a primer.

With the help of beacons, the surface of the walls of the room is displayed in one plane, after which you can begin to perform the main work.

First, finishing is done inside the premises and only then outside - otherwise excessive moisture will form inside the house.

Application technology

The appearance of the treated walls and the durability of the decorative layer depend on the correct implementation of the technology.

Below is the sequence of processing the outer surfaces of aerated concrete walls.

First you need to inspect the blocks: eliminate all irregularities, clean the cracks, expand and putty with a regular mortar.

In the same way, they act when detecting chips and potholes in each gas block. The listed preparatory work can be done with your own hands - it's not difficult at all.

Those who dare to do the basic work with their own hands without the appropriate skills need:

get tools;
follow the technology of performing plastering works;
not be afraid of heights (part of the time will have to be spent at a decent height in the forests);
have free time;
have physical powers.

In order for the plaster to lay down well and not lag behind, gas blocks are primed after cleaning with a metal brush.

A special primer is required - it must contain acrylate siloxane. This ingredient protects the wall from moisture and increases adhesion. At the same time, the composition does not prevent the gas block from "breathing".

The priming operation in accordance with the technology should be carried out in dry weather and an ambient temperature of about +15 degrees. It is advisable to process the walls from the side where there is no direct sunlight.

The next stage - mesh tension - is started after the final absorption of the primer.

For gas blocks, a mesh made of alkali-resistant material is suitable. Any other material will simply dissolve over time, which will negatively affect the service life of the finishing layer. On the wall, the fiberglass reinforcing mesh is fixed with self-tapping screws so that there is a small space between it and the wall.

Plastic plaster, specially designed for aerated concrete, is applied to the prepared wall in dry, warm weather. Mixtures for foam building material are quite expensive, but they repel moisture and allow air to pass through. The plaster is applied to the blocks with a wide spatula.. The result should be an even thin layer, the thickness of which is approximately 8 mm.

This is not the end of the processing. A water repellent is applied to the plaster. After it is absorbed, it's time for the final finishing. The choice can be decorative plaster or paint. In both cases, the compositions are distinguished by "breathing" abilities, which guarantee the unhindered passage of vapors from inside the room to the outside.

The processing of aerated concrete walls inside the house begins in the same way as outside. In the same way, an inspection is carried out, and significant shortcomings are annulled. Before puttying surfaces, the leveled wall is primed.

Interior decoration is carried out with special plaster, which includes gypsum and perlite sand.

After the work is completed, the walls become homogeneous, smooth, without the slightest visible defects. The consumption of plaster is small, because the layer is superimposed very thin. This eliminates the need for long alignment, which is also important.

Interior walls should be painted with paints specially designed for aerated concrete. They can be applied to both ordinary plaster and decorative. Painted surfaces look great - decorative finishes retain their original appearance for a long time.

The construction of houses from gas silicate blocks is one of the most promising areas in the field of private construction. In particular, aerated concrete blocks have gained great popularity, during the production of which special additives are introduced into the composition of the solution, causing abundant gas formation. As a result, aerated concrete has a pronounced open porous structure, which determines its significant advantages over other materials for masonry walls.

However, such a structure of aerated concrete also brings a number of difficulties in finishing the erected walls. A special approach is needed here, both in terms of the sequence of work and the materials used. In addition, the plastering of aerated concrete walls inside the room will also depend on their planned exterior finish.

What is the "capriciousness" of aerated concrete in matters of finishing, and how these problems can be solved - this publication is devoted to these issues.

Features of aerated concrete

But the materials for the work should go through in more detail.

The open porous structure of aerated concrete will not allow you to limit yourself to only puttying the walls - a thin layer simply will not hold on to such a surface. Therefore, even if the wall is laid out with the highest precision and does not require special adjustments to its plane, you still cannot do without plaster. And on the aerated concrete wall you will have to “throw” a layer of at least 5 mm.
Such a layer will be prone to cracking and shedding (adhesion features of a highly porous structure affect), if it is not reinforced with a reinforcing mesh. If on other wall materials the use of a reinforcing mesh is desirable, then in the case of aerated concrete this condition should be considered as mandatory. The mesh is best - fiberglass, resistant to alkaline environment, so that over time it simply does not dissolve in the thickness of the hardened plaster mass.

The use of reinforcing fiberglass stacks is a prerequisite for high-quality plaster

Aerated concrete walls are distinguished by high moisture absorption. As experienced painters say, this material literally “drinks” water. It would seem that this is not bad for good adhesion, but it turns out just the opposite. Aerated concrete "sucks" moisture from the applied one, which causes it to dry out quickly, crack and shed - in the case of gypsum compositions, and disrupt the normal hydration of cement, if plasters based on it are used. In both cases, the quality of the coating will be low, and the finish itself will be extremely short-lived.

It is important to find the “moisture balance” correctly, otherwise the work will be of poor quality.

On the other hand, excessive saturation of aerated concrete with water is also fraught with negative consequences. Yes, and such a wall is very difficult - the thrown mortar begins to "creep", the layer becomes loose or inhomogeneous, etc.

Which exit?

- you can use special plaster mixtures specifically for aerated concrete, intended for interior finishing work. Their component composition, when properly mixed with water, in accordance with the instructions, is fully optimized for the characteristics of such a surface and even sometimes does not require preliminary priming of the surface. All this is mandatory indicated by the manufacturer in the instructions for use of the composition.

— application of special primers of deep penetration. Here, however, balance is also important - oversaturation of aerated concrete with impregnating compounds can lead to the opposite effect, since the absorbency of the surface for applying plaster on it is still important.

In both cases, professional masters do not advise immediately to give a thick sketch - it is best to limit yourself to a minimum layer in which a reinforcing fiberglass mesh is embedded. Such a layer does not require a large amount of moisture, it is much easier to “wipe” it into aerated concrete with an effort, and reinforcement will create a solid foundation, without cracks. But after drying such a substrate, it will be possible to safely proceed to the main plastering along the lighthouses.

Video: the work of an aerated concrete wall plastering master

As already mentioned, the composition of the plaster mixture directly depends on whether it is necessary for the wall to leave its high vapor-permeable properties, or, conversely, to make it as difficult as possible for moisture to penetrate the material.

In the first case, preference is often given to special gypsum-based plasters, which often include light perlite sand. Usually, the instructions for use of the composition indicate that it is combined with aerated concrete (gas silicate) walls. A classic example of such mixtures is Plaster or Osnovit-Gypswell plasters.

Manufacturers claim that the application of such compounds does not even require a reinforcing mesh. But in the case of aerated concrete, this point is better not to be ignored.

Silicate plasters, based on, are very well suited for aerated concrete, especially in terms of vapor permeability. However, such wall decoration will significantly limit the owners in choosing a finish coating, since silicate mixtures are incompatible with many other organic-based decorative compositions - acrylic, silicone, latex, etc.
Especially for aerated concrete or similar surfaces, cement-lime-based plasters have been developed. Their composition is optimized specifically for such surfaces that do not even require preliminary priming before plastering. An example is Baumit HandPutz plaster or a mixture from a set of a whole "ensemble" of mortars specially designed for AeroStone aerated concrete.

The composition of such plasters includes cement, building lime, special light aggregates and plasticizing additives, fine-grained purified sand. Such a coating has good vapor permeability, and can be used for both external and internal work on aerated concrete.

If in the plans of the owners of the house to achieve a minimum vapor permeability of the walls from the inside, then they usually resort to the use of cement-sand plasters without inclusions of lime or dolomite chips (flour). Naturally, the composition usually includes special plasticizing additives that suffocate the adhesion of the coating being created with a porous base.

All specialized mixtures for gas silicate surfaces have one common drawback - they are quite expensive, and with large volumes of work, such internal plastering of walls will result in a fair amount. But this is only a preliminary alignment, without finishing! Is it possible to do it easier, use more affordable mixtures or generally ordinary home-made plaster solutions, for example, based on cement and sand?

It is possible, but only an experienced master can perform such a finish with high quality, to whom his many years of practice allows him to "by eye" determine the condition of the wall, and the need for moisturizing or priming it, and the exact component composition of the plaster. And without the experience of such work, making a mistake on an aerated concrete surface is as easy as shelling pears, and all the work will be done in vain.

However, one very interesting way to pre-prepare the gas silicate wall for the future can be recommended. If everything is done in accordance with the recommendations, it will be possible to apply almost any plaster composition without fear for the appearance of cracks, slipping of the solution, its rapid drying, or, conversely, excessive waterlogging of the wall.

How can I qualitatively prepare an internal aerated concrete wall for plastering

To work, you will need the usual, most inexpensive of all presented in the store, ceramic tile adhesive, fiberglass mesh, deep penetration primer (normal, such as Ceresit CT 17). And then it will be possible to plaster with any composition on a gypsum, cement, cement-lime and other basis. In particular, the usual cement-sand mixture is quite suitable, even in a ratio of 1: 5.

It is rather difficult to determine in advance the amount of plaster mixture to put the wall in order, since it depends on the condition of the surface, its evenness, the presence and depth of level differences both vertically and horizontally. But our calculator will help determine the amount of materials for the preparatory cycle.

It takes into account the conditions for priming the surface in two layers, moreover, with the dilution of the primer with water during the initial application, and the creation of a preparatory reinforced adhesive layer 5 mm thick. Calculations will show the result with the 15% margin "just in case" accepted by builders-finishers.

The calculation is carried out for rectangular surfaces, minus window and door openings.

Plastering walls made of aerated concrete indoors is one of the topical issues in the construction of gas blocks. The fact is that the material needs to be plastered for a number of reasons, the main of which are the cleanliness and smoothness of the surface, since without additional measures the finishing layer will not hold well. To make it clearer, all these nuances should be understood in detail.

Aerated concrete blocks are characterized by ease of use: the material is warm and light. This facilitates their trouble-free cutting to obtain the required dimensions. However, a completely logical question may arise, why do we need aerated concrete plaster? The fact is that the blocks have a smooth surface, which will not allow you to properly fix the finishing layer. In this case, the choice of plaster mixtures for a gas block should be approached very carefully. Plastering walls from the inside allows you to solve the following tasks:

protects the surface from sudden temperature fluctuations;
provides a good level of adhesion to other materials;
improves thermal insulation characteristics;
provides vapor permeability;
protects against moisture.

It should be borne in mind that aerated concrete, like foam concrete, has a cellular structure. Therefore, plastering must be carried out in compliance with the technology. Otherwise, air circulation is disturbed, which leads to a deterioration in the properties of the material. Plastering of aerated concrete walls outside the premises is also necessary. The outer finish protects against the effects of precipitation and the accumulation of harmful gases and dust.

When to plaster?

The gas block, due to its porous structure, easily absorbs moisture, so it must be immediately protected from such a negative impact. If the building material gets wet, there is nothing critical in this. However, you should not allow freezing of water in the block. As a result, cracks may simply appear, the strength will decrease, and there is no need to hurry with the cladding. After the masonry is completed, the walls must dry. Therefore, aerated concrete walls must be plastered only in heat. If the blocks are not laid on a special adhesive mixture, due to which a seam of small thickness is provided, the drying time increases.

There are situations when in the warm season it is not possible to perform finishing work. In this case, the walls are covered with deep penetration soil, which will reduce moisture absorption. In addition, it is recommended to cover the walls with plastic wrap. If you follow the advice of the masters, then it is best to finish the walls of aerated concrete during the period when the temperature at night does not fall below 0˚С. Depending on the region, such temperature indicators correspond to the time from late March to early October. From the above, we can conclude whether it is necessary to plaster aerated concrete walls.

Types of plaster mixes

Before you figure out how to plaster aerated concrete walls, you need to decide on the materials that are suitable for these purposes. Building mixtures can be purchased ready-made or kneaded independently immediately before application. To prepare a high-quality solution, it is necessary to use a filler, which is used as sand, gravel, sawdust or stone chips and an astringent (slaked lime, clay, gypsum, cement). Water is added to these components. Cement-sand plaster and mixtures, which use slaked lime, cement and sand, are prepared at the construction site. To date, clay is used quite rarely.

As for ready mixes for plastering, they are supplied in dry bags. They include:

cement;
gypsum;
sand;
fillers.

Such mixtures are divided into cement and gypsum, which have their own properties and features in application. Cement-based compounds have a longer drying time, are subject to cracking and sedimentation. Plaster on aerated concrete is applied in a layer 5-10 mm thick.

What mixture to choose?

All the mixtures that were listed above have different properties and, when applied to a building material, act differently. But the question of which plaster is better to plaster aerated concrete walls remains open. First, consider what is used to protect the outer walls, which are constantly affected by precipitation, wind and temperature. As a rule, these are mortars based on cement and sand. They have proven themselves in constant contact with moisture. But the question is - can they be used for plastering aerated concrete? Due to the porous structure, the gas block quickly absorbs moisture, as a result, the cement simply does not have time to gain the necessary strength.

To plaster aerated concrete walls with cement mortar, you need to do it right, i.e. with technology. To prevent moisture from the building mixture from being absorbed into the block, the surface must be prepared. For this purpose, it is covered with several layers of a deep penetration primer, with each layer being completely dry before applying the next. Before applying the plaster, the surface of the wall is wetted. To avoid cracking, it is recommended to use a mesh.

How to plaster aerated concrete inside the house? Gypsum mortars, unlike cement mortars, dry faster, and the surface is less prone to cracking. Mixtures based on gypsum are used for partitions and internal walls, since such compositions are of little use for outdoor use due to the constant influence of moisture. Ready plaster mixtures contain various additives and fillers in their composition, due to which the surface is endowed with resistance to cracking and negative influences.

If there is a choice between the finished mixture and the one made before use, then it should be taken into account that the properties of dry plaster are more predictable. In the process of production of such compositions, the moisture content of the sand, the quality of the cement, the accuracy of all components are controlled. As for mixtures that are prepared on site, it is quite problematic, if not impossible, to check the quality of cement. The main disadvantage of dry plasters is the high cost.

Preparatory activities

To fully answer the question of how to properly plaster an aerated concrete surface, it’s worth starting with the tools that you need to work. In fact, the tools used are the same as for applying a traditional plaster mixture. To prepare the solution, you will need a container, which can serve as a plastic bucket or tank. By volume, they should be sufficient to stir all the components.

After pouring the dry mixture into the container, add water. To mix the solution, use a construction mixer or a drill with a nozzle. To achieve the required consistency, the proportions of water and material are determined according to the inscriptions on the bags with dry plaster. To work, you will need the following tools:

Master OK;
plaster ladle;
trowel.

Plastered aerated concrete is rubbed with a grater, while the excess mortar is removed with a trowel. Beacons are used to level the surface, the solution is pulled together using the rule. An obligatory tool for checking defects on the surface of the walls is a long rail from floor to ceiling. The maximum deviation should be no more than 7 mm.

Plastering the surface from the inside

After deciding how to plaster aerated concrete, proceed directly to the workflow. As with any other type of finish, you first need to prepare the surface. Gas blocks must be cleaned of the remnants of the masonry mixture and seal the seams. As already noted, a primer is applied before plastering. Internal plastering of aerated concrete walls consists of the following steps:

Reinforcing mesh attachment. To increase the strength of the rough finish, you can use a chain-link mesh with a small mesh size. In addition, a reinforcing material with alkali-resistant fiber is added to the composition of the mixture. The mesh is fastened with nails 120 mm long, which are well driven into the aerated concrete wall.
If the reinforcement process is not expected, it is necessary to make special grooves for better adhesion of the surface of the block with finishing materials. For these purposes, use any suitable tool, such as a hacksaw.
Applying the plaster mixture on the reinforced base. In this case, they resort to applying the mixture by spraying, when the voids of aerated concrete are completely filled. The first layer of plaster is not leveled, which will provide better adhesion.

A primer must be applied over the rough layer of plaster. It is recommended to add slag sand to the priming solution. It is desirable to apply the finishing layer of plaster using building mixtures with fine sand in the composition, which allows you to get a smoother surface. At the end of the process, the already dried solution is smoothed to make the surface as even as possible. As a rule, smoothing is started 24 hours after application. To make the surface smoother, the blocks are sprayed with water.

The final stage is painting work, which involves the use of paints. Materials in this case are selected with a high degree of vapor permeability. After the surface is painted, it is recommended to apply a water repellent, which will increase the durability and strength of the finishing layer. The lifespan of an interior finish depends on many factors. One of the main ones is the quality of the materials used, i.e. should be based on cost. The characteristics of the gas block are no less important, because even a good finishing mixture will not hold well on a low-quality surface.

Exterior wall plastering

The most budgetary and common plaster for outdoor use is cement-sand. However, the mixture is not suitable for aerated concrete due to low vapor permeability. For these purposes, mineral, silicate or silicone facade plasters are used. They have a number of necessary characteristics: vapor permeability identical to aerated concrete, good adhesion, have a beautiful appearance. They start plastering the facade only after the completion of all processes, as a result of which moisture is released inside the room, and the surfaces are completely dry. Gas blocks must be dry, and the maximum allowable humidity is 27%. If this figure is too high, the water vapor that will escape to the outside will cause peeling of the finishing layer. Facade plaster for aerated concrete should be endowed with the following qualities:

frost resistance;
high adhesion to the base;
increased compressive strength;
weather resistance;
decorative.

Plaster for exterior decoration can be applied to the walls of the house in a thick layer (thick layer) or thin (thin layer). Thin-layer plaster is characterized by the fact that the material is applied in several layers with a thickness of not more than 10 mm. After preparing the surface and covering with soil, a thin layer of plaster (up to 5 mm) is applied and reinforced with a mesh.

For reinforcement, metal (wire diameter - 0.1 mm, mesh size - 0.16 * 0.16 mm) or fiberglass mesh (mesh size - 50 * 50 mm) is used. Its installation is carried out with an overlap of 50 mm. In addition, the corners of the building are formed, for which a perforated corner with a mesh is used, which prevents the appearance of cracks due to shrinkage of the building. Using a spatula, the mesh is sunk into the applied mixture. Reinforcing material must be installed at the locations of doors and windows. Then the plaster layer is leveled and waiting for it to dry. The second layer is considered leveling, so you need to strive to create the smoothest possible surface. After the finishing layer is applied and the surface is rubbed with subsequent grouting. It remains to cover the building outside with paint, apply textured plaster and a water repellent.

The approach to plastering the internal surfaces of aerated concrete walls is somewhat different from similar work on brick and concrete walls.

From this article, you will learn what exactly should be considered when plastering aerated concrete, how to properly solve the issue of vapor barrier, and which mixture is best to use. The sequence of do-it-yourself work, corresponding to the correct technology for plastering aerated concrete and the ratio of the proportions of the solution, will also be considered in stages.

There are two options here: use materials for a vapor-permeable finish, which will not interfere with the original properties of the gas block, or use a vapor barrier finish, which significantly reduces the vapor permeability coefficient of the material.

The first option is good because the vapor permeability of the walls of the house contributes to the fact that the microclimate in the building will constantly self-regulate, as a result of which life in it will be as comfortable as possible, you will not need to worry about dampness, the formation of fungi or mold on the inner surface of the walls.

By artificially reducing vapor permeability, you will lose all this, but you will get a more durable layer of facade plaster at home.

The fact is that it is the steam coming out of the inside of the house through its walls that is the main cause of cracking of the outer plaster coating in the cold season.

This happens because of the "dew point" - when steam, the temperature of which is lower than the air temperature, condenses on the surface of the wall under a layer of external plaster, freezes, and provokes peeling of the cladding.

The choice of the type of plaster mixture lies entirely on your shoulders. You must approach it as responsibly as possible, and be fully aware of what exactly you want to receive and what you are sacrificing in return.

Feedback from builders responsible for plastering walls from a gas block indicates that most customers prefer the option of a vapor-permeable finish.

1.2 What is the best plaster to use?

As can be understood from what has been read above, there are two types of plaster mixtures for finishing aerated concrete walls inside the building - vapor barrier and vapor permeable.

Vapor-permeable plaster mixtures include gypsum-based mixtures in proportion. The best option, which has the best value for money, is the Pobedit Aegis TM35 plaster mix, which includes lime.

Aegis TM35 (lime) has all the properties that should be inherent in a high-quality mixture for aerated concrete - minimum weight, high adhesive properties, and hardened layer strength.

This mixture is based on gypsum (lime) and perlite sand, it also contains slaked lime, which guarantees the maintenance of optimal vapor barrier characteristics of the walls of the house.

If no additional wall cladding is planned after the plaster layer (painting the plaster layer is a fairly common design solution today), then you should give preference to the Aegis S50 mixture, which includes lime.

This material, although it has a slightly lower vapor conductivity, due to the presence of a 2.5% concentration of polymer impurities in the composition, guarantees maximum strength and whiteness of the walls, since the mixture is based on lime and gypsum with a fraction size of 60 to 90 microns, which is 30-50 percent less than products in the same price range.

The category of vapor barrier plaster mixtures includes materials that include a large amount of polymer impurities - this is plastic plaster that has recently gained wide popularity.

This also includes conventional cement-sand plaster, the composition of which does not contain additives in the form of lime, or dolomite flour. To ensure maximum vapor barrier (reduction of steam transmission by 11-12 times), it is required to apply a composition of sand-cement plaster with a thickness of 2-2.5 centimeters. For large areas, a sand-cement plastering station can be used. Since plastering the walls with a cement-sand mortar of a room is not an easy task.

There are also more radical inexpensive ways to reduce the vapor conductivity of aerated concrete walls, for example, lining a conventional polyethylene film under a layer of plaster, however, this method is not recommended due to the fact that peeling of the finish from the walls may occur due to the formation of condensate on the surface of the film.

The most cost-effective option for vapor barrier plastering of the internal walls of an aerated concrete house is the composition of an ordinary inexpensive gypsum mixture together with vapor barrier primers such as Pobedit Grunt-Concentrate and the like.

To achieve the desired effect, you will have to prime the walls of the gas block 3-4 times, which will reduce the vapor permeability of plaster with a thickness of 10 millimeters by almost 5 times.

It is also worth considering the surface finish of the room, for example, plaster painted with oil paint loses about 30% of the composition in steam transfer, wallpapering, especially fleece, also contributes to a similar effect.

2 Required tools and work technology

The composition of the tools by which the plastering of the internal surfaces of the walls from the gas block is carried out is no different from the tools for similar work on other surfaces.

You will need a container in which the plaster mixture will be mixed.- a plastic or metal bucket or tank, the main thing is that the size fits. For high-quality mixing, a drill with a mixing nozzle is required, so it is quite difficult to bring the mixture to the desired consistency with your own hands - clots and lumps will form.

The proportion ratio and composition of the dry mix and water are indicated by the manufacturer on each package, do not neglect these recommendations, as they may vary for different plasters.

A mixture of plaster is thrown onto aerated concrete using a trowel or a special plaster ladle. Leveling and plastering is carried out by means of a profil and spatulas.

If you need to apply a thick, over 1 cm, layer of plaster on the wall, then it is recommended to purchase plaster beacons for plastering, which greatly simplify leveling and plastering with mortar. You can rub the surface with a plaster grater, or ordinary fine sandpaper.

If the walls are covered with a thick layer of plaster, then it is necessary to use a reinforcing mesh that will strengthen the finishing layer and prevent it from cracking and peeling.

Also, the mesh improves the adhesion of the solution and the gas block, as a result, it is much easier to apply the mixture to the wall surface. It is best to use plaster fiberglass meshes with a mesh size of 5 × 5 mm.

Stages of work:

We prepare the surface - we clean the walls of dust, glue residues, and any contaminants. Oil stains are degreased with alcohol or gasoline. If the stain cannot be processed, then it is necessary to hollow it out of the gas block, and repair the formed unevenness with plaster mortar.
The walls are covered with a layer of primer. The number of layers is determined by the technology and the requirements for the vapor permeability of the walls, while applying the next layer, you must wait until the previous layer is completely dry.
If necessary, a reinforcing mesh is mounted on the walls. The mesh should be installed tightly, without sagging - this is best done using dowels with wide caps.
A rough layer of plaster mixture is applied. The solution is evenly sprayed on the wall with a trowel, and leveled with a rule.
After setting the rough layer, it is covered with a primer and carefully leveled.
After the complete hardening of the draft layer, the wall is plastered with a finishing mixture, which is leveled with a spatula.

After two days after applying the finishing putty, you can start decorative finishing work.